In process and automation technology, field devices are applied for determining and/or monitoring process variables, including physical or chemical process variables. A field device typically includes at least one sensor unit coming at least partially and at least at times in contact with the process. Referred to as field devices in the case of the present disclosure are, in principle, all measuring devices, which are applied near to the process and which deliver, or process, process relevant information. Involved, for example, are fill level measuring devices, flow measuring devices, pressure and temperature measuring devices, pH-redox potential measuring devices, conductivity measuring devices, etc., which register the corresponding process variables, fill level, flow, pressure, temperature, pH-value, and conductivity. Such field devices are manufactured and sold in various embodiments by the E+H group of companies.
Such field devices contain, generally, electronic components, which are usually arranged and soldered with one another on a planar circuit board. Often, in such case, a number of circuit boards are installed in a non-conductive housing of the field device or a conductive housing having at least a non-conductive surface, wherein typically the planes of the different circuit boards are oriented parallel to one another in the housing. In such case, one or more electrical contacts are provided between the circuit boards, which serve, for example, for electrical current supply or for data transfer between the different circuit boards. Such circuit board arrangements in a housing are used in the most varied of field devices of the Endress+Hauser group.
Generally in such case, additional components, which serve for electrical contact between the circuit boards arranged and secured in the housing, must be installed in an additional method step. For example, during populating the circuit boards, a socket is soldered on a first circuit board and a plug fitting the socket is soldered on a second circuit board to be connected with the first circuit board. The socket and the plug must then be brought together in suitable manner in an additional working step during the arranging of the two circuit boards in the housing.
Alternatively to contacting with socket and plug, known from the state of the art are flexible, flat connection elements for electrical contacting of circuit boards. Examples of these flexible connection elements, also referred to as jumpers, are given in U.S. Pat. No. 6,614,664 B2 and Offenlegungsschrift DE 10 2004 037 629 A1. These flexible connection elements are soldered onto two circuit boards adjoining in a plane. This is done, for example, during the populating of the circuit boards with electronic components. The flexible connection elements have, compared with the connection with plug and socket, the advantage that the connection of two circuit boards occurs during the populating of the circuit boards with electronic components and, thus, no additional working step is necessary for effecting the connection. The flexibility of the flexible connection elements enables electrical contacting of the rigid, planar circuit boards to be led from the plane of the circuit boards uninterruptedly into another dimension. This is accomplished by bending or folding the flexible connection elements. If the two adjoining circuit boards are displaced from the shared plane and arranged in two mutually parallel planes, the flexible connection elements can, in such case, be formed, by bending and/or folding, to extend in a direction perpendicular to the circuit board plane.
In principle, it is also possible to provide a number of flexible connection elements between two neighboring circuit boards. In such case, there are, however, significant limitations on the arrangement of the flexible connection elements because they all must be arranged in a shared edge region (i.e. a shared bending edge or folding edge). Such an arrangement of the connection elements between circuit boards is not always possible since the flexible connection elements permit, generally, no more than two circuit boards to be connected without significant limitations on the spatial positioning of the flexible connection elements relative to the circuit boards.
For use of field devices in explosion endangered regions, in contrast, safety regulations for explosion protection require a spatial isolation of certain regions or certain electrical contacts. In such case, of concern, especially, is to safely prevent the forming of sparks or at least to assure that a spark possibly occurring in the interior of a closed space has no effects on the environment, in order, so, to safely avoid a possible triggering of an explosion. For example, European Standard EN 60079-7:2007 provides a protection class bearing the label “Increased Safety” (Ex-e). In the case of electronic devices, which are embodied to meet this protection class, the ignition, or explosion, protection is achieved by making the spatial distance between two different electrical potentials sufficiently large that a spark formation in the case of malfunction cannot occur, due to the distance.
For use of the field device in an explosion endangered region, it is, consequently, desirable to provide an automatable and cost-effective method for electrical contacting of circuit board arrangements in a housing of a field device, which method enables significant freedom relative to the spatial arrangements of the electrical contacts.